The present invention relates to sulkies for self-propelled walk behind mowers and, more particularly, to a sulky that provides a clevis on the operator platform for attachment to a vertical pivot point on the hitch arm. The improvement improves control of the distributive forces and loads of the sulky and, thereby, prevents unnecessary structural failures in the vertical pivot point.
Sulky devices have been used in conjunction with power mowers for many years and are, thus, well known in the prior art. Sulkies were originally used with mowers in a general trailer type fashion without the use of pivots. For example, U.S. Pat. No. 2,218,064 to G. A. Amsbury entitled xe2x80x9cRiding Trailerxe2x80x9d discloses a riding trailer which can be hitched to the rear of a lawn mower by two side bars. The riding trailer has a seat situated above a supporting wheel and the user is provided with foot controls to guide the movements of the lawn mower. A shortcoming of this invention is that the side bars prohibit rotation of the trailer with respect to the lawn mower and, thereby, do not permit use of the lawn mower to manipulate through narrow turns in a specific area.
Later, sulkies were designed to incorporate the use of a vertical pivot point at the attachment of the sulky to the mower. For example, U.S. Pat. No. 5,118,123 to Betrock entitled xe2x80x9cStanding/Sitting Lawn Mower Trailerxe2x80x9d discloses a system in which a trailer hitches to a self-propelled lawn mower. The trailer has an elongated towbar which is adjusted and locked to the lawn mower. Similarly, U.S. Pat. No. 5,388,850 to Simone entitled xe2x80x9cConvertible Sulkyxe2x80x9d discloses an H-shaped support wheelbase frame member with a T-shaped mower attachment frame. The H-shaped support wheelbase is attached to the mower through a ball-hitch fixture on the frame. A shortcoming of these devices is that by placing the vertical pivot point so close to the mower, the turning radius of the sulky with respect to the mower is limited since the sulky swings out from behind the mower during a turn, often at a distance greater than an operator is able to control. Thus, devices having an elongated towbar or frame that pivot at the mower/sulky junction only do not permit rotation of the trailer or sulky with respect to the lawn mower and, therefore, neither the trailer nor the sulky permit the user to maneuver through a narrow or small turning radius.
A vertical pivot point located at the attachment of the sulky to the lawn mower provides a sulky that is more stable for the operator, but less maneuverable, as exhibited by the patents in the preceding paragraph. Conversely, the reverse is true. A vertical pivot point located along the hitch arm of the sulky and not directly with the lawn mower provides a sulky that is less stable, but more maneuverable.
To accommodate increased maneuverability, sulkies have been designed with vertical pivot points along the attachment arms to enable the lawn mower to maneuver through a narrow or small turning radius or as desired by the user. For example, U.S. Pat. No. 5,004,251 to Velke et al. entitled xe2x80x9cSulky Apparatus Attachable To A Self-Propelled Power Mowerxe2x80x9d discloses a sulky apparatus that is attachable to a self-propelled power mower to transport an operator in the standing position. The sulky provides a first arm connected to the lawn mower through a horizontal pivot point and a second arm connected to the operator platform. The first arm and the second arm are connected through a vertical pivot point permits movement of the operator platform about the vertical pivot point. In this fashion, the lawn mower can better navigate tight turns.
Likewise, U.S. Pat. Nos. 5,810,371 and 5,882,020 to Velke entitled xe2x80x9cSulky Device With Triple Pivot Attachment To Mowerxe2x80x9d disclose the sulky in U.S. Pat. No. 5,004,251 with a third pivot point located at the connection of the second arm to the operator platform and an additional wheel to form a two-wheeled sulky. The third pivot point operates along the horizontal axis and theoretically provides a storage position for the operator platform with respect to the lawn mower.
Although these sulkies permit operation in small areas, they do not, particularly in single wheel sulkies, leverage the forces and loads on the vertical pivot point as applied by the weight of the operator and torque of the mower. Therefore, the vertical pivot point is susceptible to uncontrollable bending or structural failure of the vertical pivot point. Also, the uncontrollable bending or structural failure requires that the weight of the operator must be limited to reduce the counterbalancing forces on the vertical pivot point. Therefore, these sulkies are not practical for all consumers.
Another shortcoming of these sulkies is that the vertical pivot point permits 360xc2x0 rotation about the first arm. The inherent danger with the free rotation is that a user is vulnerable to injury if positioned on the operator platform as the second arm rotates the operator platform to cross under the first arm.
In the prior art designs, placing the vertical pivot point away from the lawn mower and closer to the operator platform leads to unnecessary torquing which, in turn, causes premature sulky failure. Further, the design of these sulkies is suited best in a two wheel design as the torque forces are exacerbated in a single wheel sulky since the operator must balance himself. In spite of this problem, many operators prefer single wheeled sulkies over two wheeled sulkies because they maneuver better.
Thus, there is a need and there has never been disclosed a sulky that provides counter balance and reduction of the forces and loads as applied to the vertical pivot point to prevent the unnecessary structural anomalies and failures in the vertical pivot point.
It is the primary object of the present invention to prevent unnecessary structural anomalies and failures in the vertical pivot point of sulkies. A related object of the present invention is to reduce the forces and loads applied to the vertical pivot point that result from the weight of the operator and the torque supplied by the operation of the lawn mower. This is provided for in an operator platform with a clevis to affix to a vertical pivot point on a hitch arm. The clevis is adapted to receive the vertical pivot point on the hitch arm and to coact with the vertical pivot point to secure a hinge and, thereby, attach the operator platform to the hitch arm.
Another related object of the present invention is to provide a means to counter balance the forces and loads applied to the vertical pivot point.
Still another object of the invention is to permit the use of the sulky device by heavier operators.
Still another object of the invention is to prohibit unlimited rotation of the operator platform about the vertical pivot point to provide increased safety to the operator.
Still another object of the invention is to provide an increased useful life for the vertical pivot point. A related object of the invention is to reduce the costs associated with repairing a damaged vertical pivot point. A further related object of the invention is to provide the user with a more reliable sulky.
Other objects of the present invention will become more apparent to persons having ordinary skill in the art to which the present invention pertains from the following description taken in conjunction with the accompanying drawings.
The objects of the present invention are provided for in a sulky having an improved attachment interrelationship between an operator platform and a hitch arm that connects the sulky to a self-propelled walk behind lawn mower. The operator platform is attached to the hitch arm through a vertical pivot point and a generally C-shaped clevis.
The hitch arm is connected at one end to the rear of a mower. The opposite end of the hitch arm is fitted with a vertical pivot point. The vertical pivot point comprises a vertical pivot tube and a corresponding vertical pivot pin. Preferably, the clevis has a top support member, a bottom support member, and an operator platform support member. The top and bottom support members extend essentially horizontally from the front of the operator platform and essentially parallel to one another at a predetermined vertical distance from one another. The vertical pivot point is inserted into the opening of the space created by the vertical distance between the top and bottom support members, the vertical pivot point then being secured to the clevis by a vertical pivot pin that is inserted into holes found in the top support member, vertical pivot tube, and bottom support member.